RDMA/uverbs: Use the iterator for ib_uverbs_unmarshall_recv()

This has a very complicated memory layout, with two flex arrays. Use
the iterator API to make reading it clearer.
Signed-off-by: Jason Gunthorpe <jgg@mellanox.com>
Signed-off-by: Leon Romanovsky <leonro@mellanox.com>
Signed-off-by: Doug Ledford <dledford@redhat.com>

drivers/infiniband/core/uverbs_cmd.c

@@ -150,6 +150,17 @@ static int uverbs_request_next(struct uverbs_req_iter *iter, void *val,
 	return 0;
 }
 
+static const void __user *uverbs_request_next_ptr(struct uverbs_req_iter *iter,
+						  size_t len)
+{
+	const void __user *res = iter->cur;
+
+	if (iter->cur + len > iter->end)
+		return ERR_PTR(-ENOSPC);
+	iter->cur += len;
+	return res;
+}
+
 static int uverbs_request_finish(struct uverbs_req_iter *iter)
 {
 	if (!ib_is_buffer_cleared(iter->cur, iter->end - iter->cur))
@@ -2073,16 +2084,23 @@ static int ib_uverbs_post_send(struct uverbs_attr_bundle *attrs,
 	int				is_ud;
 	int ret, ret2;
 	size_t                          next_size;
+	const struct ib_sge __user *sgls;
+	const void __user *wqes;
+	struct uverbs_req_iter iter;
 
-	if (copy_from_user(&cmd, buf, sizeof cmd))
-		return -EFAULT;
-
-	if (in_len < sizeof cmd + cmd.wqe_size * cmd.wr_count +
-	    cmd.sge_count * sizeof (struct ib_uverbs_sge))
-		return -EINVAL;
-
-	if (cmd.wqe_size < sizeof (struct ib_uverbs_send_wr))
-		return -EINVAL;
+	ret = uverbs_request_start(attrs, &iter, &cmd, sizeof(cmd));
+	if (ret)
+		return ret;
+	wqes = uverbs_request_next_ptr(&iter, cmd.wqe_size * cmd.wr_count);
+	if (IS_ERR(wqes))
+		return PTR_ERR(wqes);
+	sgls = uverbs_request_next_ptr(
+		&iter, cmd.sge_count * sizeof(struct ib_uverbs_sge));
+	if (IS_ERR(sgls))
+		return PTR_ERR(sgls);
+	ret = uverbs_request_finish(&iter);
+	if (ret)
+		return ret;
 
 	user_wr = kmalloc(cmd.wqe_size, GFP_KERNEL);
 	if (!user_wr)
@@ -2096,8 +2114,7 @@ static int ib_uverbs_post_send(struct uverbs_attr_bundle *attrs,
 	sg_ind = 0;
 	last = NULL;
 	for (i = 0; i < cmd.wr_count; ++i) {
-		if (copy_from_user(user_wr,
-				   buf + sizeof cmd + i * cmd.wqe_size,
+		if (copy_from_user(user_wr, wqes + i * cmd.wqe_size,
 				   cmd.wqe_size)) {
 			ret = -EFAULT;
 			goto out_put;
@@ -2205,11 +2222,9 @@ static int ib_uverbs_post_send(struct uverbs_attr_bundle *attrs,
 		if (next->num_sge) {
 			next->sg_list = (void *) next +
 				ALIGN(next_size, sizeof(struct ib_sge));
-			if (copy_from_user(next->sg_list,
-					   buf + sizeof cmd +
-					   cmd.wr_count * cmd.wqe_size +
-					   sg_ind * sizeof (struct ib_sge),
-					   next->num_sge * sizeof (struct ib_sge))) {
+			if (copy_from_user(next->sg_list, sgls + sg_ind,
+					   next->num_sge *
+						   sizeof(struct ib_sge))) {
 				ret = -EFAULT;
 				goto out_put;
 			}
@@ -2248,25 +2263,32 @@ static int ib_uverbs_post_send(struct uverbs_attr_bundle *attrs,
 	return ret;
 }
 
-static struct ib_recv_wr *ib_uverbs_unmarshall_recv(const char __user *buf,
-						    int in_len,
-						    u32 wr_count,
-						    u32 sge_count,
-						    u32 wqe_size)
+static struct ib_recv_wr *
+ib_uverbs_unmarshall_recv(struct uverbs_req_iter *iter, u32 wr_count,
+			  u32 wqe_size, u32 sge_count)
 {
 	struct ib_uverbs_recv_wr *user_wr;
 	struct ib_recv_wr        *wr = NULL, *last, *next;
 	int                       sg_ind;
 	int                       i;
 	int                       ret;
-
-	if (in_len < wqe_size * wr_count +
-	    sge_count * sizeof (struct ib_uverbs_sge))
-		return ERR_PTR(-EINVAL);
+	const struct ib_sge __user *sgls;
+	const void __user *wqes;
 
 	if (wqe_size < sizeof (struct ib_uverbs_recv_wr))
 		return ERR_PTR(-EINVAL);
 
+	wqes = uverbs_request_next_ptr(iter, wqe_size * wr_count);
+	if (IS_ERR(wqes))
+		return ERR_CAST(wqes);
+	sgls = uverbs_request_next_ptr(
+		iter, sge_count * sizeof(struct ib_uverbs_sge));
+	if (IS_ERR(sgls))
+		return ERR_CAST(sgls);
+	ret = uverbs_request_finish(iter);
+	if (ret)
+		return ERR_PTR(ret);
+
 	user_wr = kmalloc(wqe_size, GFP_KERNEL);
 	if (!user_wr)
 		return ERR_PTR(-ENOMEM);
@@ -2274,7 +2296,7 @@ static struct ib_recv_wr *ib_uverbs_unmarshall_recv(const char __user *buf,
 	sg_ind = 0;
 	last = NULL;
 	for (i = 0; i < wr_count; ++i) {
-		if (copy_from_user(user_wr, buf + i * wqe_size,
+		if (copy_from_user(user_wr, wqes + i * wqe_size,
 				   wqe_size)) {
 			ret = -EFAULT;
 			goto err;
@@ -2313,10 +2335,9 @@ static struct ib_recv_wr *ib_uverbs_unmarshall_recv(const char __user *buf,
 		if (next->num_sge) {
 			next->sg_list = (void *) next +
 				ALIGN(sizeof *next, sizeof (struct ib_sge));
-			if (copy_from_user(next->sg_list,
-					   buf + wr_count * wqe_size +
-					   sg_ind * sizeof (struct ib_sge),
-					   next->num_sge * sizeof (struct ib_sge))) {
+			if (copy_from_user(next->sg_list, sgls + sg_ind,
+					   next->num_sge *
+						   sizeof(struct ib_sge))) {
 				ret = -EFAULT;
 				goto err;
 			}
@@ -2349,13 +2370,14 @@ static int ib_uverbs_post_recv(struct uverbs_attr_bundle *attrs,
 	const struct ib_recv_wr	       *bad_wr;
 	struct ib_qp                   *qp;
 	int ret, ret2;
+	struct uverbs_req_iter iter;
 
-	if (copy_from_user(&cmd, buf, sizeof cmd))
-		return -EFAULT;
+	ret = uverbs_request_start(attrs, &iter, &cmd, sizeof(cmd));
+	if (ret)
+		return ret;
 
-	wr = ib_uverbs_unmarshall_recv(buf + sizeof cmd,
-				       in_len - sizeof cmd, cmd.wr_count,
-				       cmd.sge_count, cmd.wqe_size);
+	wr = ib_uverbs_unmarshall_recv(&iter, cmd.wr_count, cmd.wqe_size,
+				       cmd.sge_count);
 	if (IS_ERR(wr))
 		return PTR_ERR(wr);
 
@@ -2400,13 +2422,14 @@ static int ib_uverbs_post_srq_recv(struct uverbs_attr_bundle *attrs,
 	const struct ib_recv_wr		   *bad_wr;
 	struct ib_srq                      *srq;
 	int ret, ret2;
+	struct uverbs_req_iter iter;
 
-	if (copy_from_user(&cmd, buf, sizeof cmd))
-		return -EFAULT;
+	ret = uverbs_request_start(attrs, &iter, &cmd, sizeof(cmd));
+	if (ret)
+		return ret;
 
-	wr = ib_uverbs_unmarshall_recv(buf + sizeof cmd,
-				       in_len - sizeof cmd, cmd.wr_count,
-				       cmd.sge_count, cmd.wqe_size);
+	wr = ib_uverbs_unmarshall_recv(&iter, cmd.wr_count, cmd.wqe_size,
+				       cmd.sge_count);
 	if (IS_ERR(wr))
 		return PTR_ERR(wr);